1. Field of the Invention
The present invention relates, generally, to electronic musical instruments and, in preferred embodiments, to electronic musical instruments having the capability of detecting the amount of displacement of a pedal or of other movable members.
2. Description of Related Art
In electronic musical instruments, displacement sensors are used as sensors to detect the amount of displacement of, for example, a pedal.
Examples of prior methods for the detection of the amount of displacement are described below.
Method 1: This is a method in which, for example, a displacement sensor is configured with a rubber sensor that changes shape in conformance with the amount that a pedal is stepped on and a sensor sheet that is pressed by the rubber sensor as the rubber sensor changes shape. The resistance value of the sensor sheet changes in conformance with the area of the sheet that is pressed.
Method 2: This is a method in which the resistance value of a volume control changes in conformance with the amount that a pedal is stepped on.
The determination of the amount of displacement is possible with the use of any of the methods discussed above. However, in those cases where the displacement of a pedal is detected, the displacement sensor is required to have the durability to withstand the force that is repeatedly applied from the pedal over a long period of time. Each of the methods mentioned above has problems such as those described below.
In Method 1, when the rubber sensor is used over a long period of time and its shape is repeatedly changed in conformance with the stepping operation of the pedal, the rubber sensor becomes deformed in shape such that it becomes impossible to accurately detect the amount that the pedal has been stepped on.
In Method 2, when the volume control is used for a long period of time, the mechanical sliding portion is abraded and that becomes a problem.